Robert Drysdale is one of the few people to have submission victories over ADCC World Champions Andre Galvao and Marcelo Garcia - two of arguably the best grapplers in the world. He himself is a world champion, and was victorious in two fights in the UFC.
But being a world class competitor doesn't always translate into being a good instructor. Fortunately, Robert is also world class in this way. I got to participate in one of his classes and I loved the way he taught. I am a BJJ Black belt and have also competed in the world championships (I actually battled him in ADCC 2007), so I have seen a lot in my time. But I picked up a few tips on a basic stack pass that I never thought of before.
More importantly, I appreciated that he also focused on the mental aspect of the martial arts. Too often people are purely focused on the physical aspect. Robert went over some key details of the proper mindset for passing guard that really resonated with me.
On top of that, the guy is a class act and it reflects in his students. An instructor with good character will pass that on to his students. I had the pleasure of rolling with three of them and all were friendly, humble, and very respectful.